EMD and Zoom Envelope Spectrum for Rolling Bearing Fault Diagnosis

2013 ◽  
Vol 791-793 ◽  
pp. 841-844
Author(s):  
Jing Zhong Xiang ◽  
Hui Zhu ◽  
Meng Jin Gao ◽  
Fang Jian Chen ◽  
Xian Jiang Shi ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
High Frequency ◽  
Low Frequency ◽  
Practical Method ◽  
Rolling Bearing ◽  
Frequency Component ◽  
High Frequency Component ◽  
The Hilbert Transform ◽  
Envelope Spectrum ◽  
High Frequency Resonance

ntrinsic mode function component (IMF) has been effectively decomposed by using empirical mode (EMD) decomposition method, and the high-frequency resonance frequency band the rolling bearing components is extracted. Then the high frequency component of the IMF is shifted to the lower frequency by using real frequency modulation principle, and a new envelope refining spectrum is obtained through the Hilbert transform after low frequency sampling. The method not only simplifies the design of band-pass filtering process but improves refinement computational efficiency of the envelope spectrum. The method verifies the correctness of the theory and practical method through the analysis of the fault diagnosis of rolling bearing inner ring experiment.

The Application of Fault Diagnosis Based on EMD and Real Modulation Zoom Method

2013 ◽  
Vol 274 ◽  
pp. 37-40
Author(s):  
Jing Zhong Xiang ◽  
Fu Peng Ge ◽  
Han Sun ◽  
Xian Jiang Shi
Keyword(s):  
Fault Diagnosis ◽  
High Frequency ◽  
Low Frequency ◽  
Rolling Bearing ◽  
Hilbert Transformation ◽  
Frequency Resolution ◽  
Mode Decomposition ◽  
Shift Frequency ◽  
Envelope Spectrum ◽  
High Resonant Frequency

It is first to make Empirical Mode Decomposition (EMD) and achieve Hilbert-Hung transform (HHT) of envelope spectrum after Hilbert transformation, which can resolve the cross fault existing in Hilbert transformation is utilized merely. However, it can’t improve the resolution of envelope spectrum, which doesn’t adapt the characteristic of high resonant frequency of rolling bearing and low fault frequency. The paper utilizing the principle of real modulation shift frequency moves the EMD decomposition components of high frequency section to low frequency section and makes analysis of envelope spectrum after Hilbert transformation, which resolves the problem of low frequency resolution of pure HHT.

scholarly journals High Frequency Resonance Damping Method for Voltage Source Converter Based on Voltage Feedforward Control

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1591
Author(s):  
Bo Pang ◽  
Feng Li ◽  
Hui Dai ◽  
Heng Nian
Keyword(s):  
High Frequency ◽  
Feedforward Control ◽  
Frequency Component ◽  
Voltage Source ◽  
High Frequency Component ◽  
Voltage Source Converter ◽  
Frequency Resonance ◽  
Significant High Frequency ◽  
Resonance Damping ◽  
High Frequency Resonance

High frequency resonance (HFR) is a subsistent problem which affects the operation of the voltage source converter (VSC) connected to the parallel compensated grid. The appearance of HFR introduces a significant high frequency component in the grid voltage, thereby the operation of VSC system will be seriously affected. For enhancing the operation capability of VSC system, an HFR damping method based on the voltage feedforward control is proposed in this paper, which can reshape the VSC system impedance effectively in a wideband range. Besides, different with the existing HFR damping methods, the proposed method introduces a correction factor instead of the series virtual impedance with fixed value, so that the effect of impedance reshaping is irrelevant to the parameters of controlled object. In addition, this paper analyzes the fundamental control performance of VSC system after equipping the proposed method, for verifying that the proposed method will not worsen the fundamental control. Experimental results are given to validate the effectiveness of the proposed damping method.

scholarly journals Extreme prolongation of expiration breathing: Effects on electroencephalogram and autonomic nervous function

2018 ◽  
Vol 10 (2) ◽  
pp. 62-65
Author(s):  
Teruhisa Komori
Keyword(s):  
High Frequency ◽  
Frequency Ratio ◽  
Low Frequency ◽  
Frequency Component ◽  
Small Sample ◽  
High Frequency Component ◽  
Deep Breathing ◽  
Continuous Eeg ◽  
Nervous Function ◽  
Electrocardiogram Ecg

To clarify the physiological and psychological effects of deep breathing, the effects of extreme prolongation of expiration breathing (Okinaga) were investigated using electroencephalogram (EEG) and electrocardiogram (ECG). Participants were five male Okinaga practitioners in their 50s and 60s. Participants performed Okinaga for 31 minutes while continuous EEG and ECG measurements were taken. After 16 minutes of Okinaga, and until the end of the session, the percentages of theta and alpha 2 waves were significantly higher than at baseline. After 20 minutes, and until the end of the session, the percentage of beta waves was significantly lower than at baseline. The high frequency component of heart rate variability was significantly lower after 12 minutes of Okinaga and lasted until 23 minutes. The low frequency/high frequency ratio was significantly lower after 18 minutes of Okinaga and until the end of the session. Okinaga produced relaxation, suggesting that deep breathing may relieve anxiety. However, study limitations include potential ambiguity in the interpretation of the low frequency/high frequency ratio, the small sample, and the fact that EEG was measured only on the forehead.

scholarly journals Extreme prolongation of expiration breathing: Effects on electroencephalogram and autonomic nervous function

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
Teruhisa Komori
Keyword(s):  
High Frequency ◽  
Frequency Ratio ◽  
Low Frequency ◽  
Frequency Component ◽  
Small Sample ◽  
High Frequency Component ◽  
Deep Breathing ◽  
Continuous Eeg ◽  
Nervous Function ◽  
Electrocardiogram Ecg

To clarify the physiological and psychological effects of deep breathing, the effects of extreme prolongation of expiration breathing (Okinaga) were investigated using electroencephalogram (EEG) and electrocardiogram (ECG). Participants were five male Okinaga practitioners in their 50s and 60s. Participants performed Okinaga for 31 minutes while continuous EEG and ECG measurements were taken. After 16 minutes of Okinaga, and until the end of the session, the percentages of theta and alpha 2 waves were significantly higher than at baseline. After 20 minutes, and until the end of the session, the percentage of beta waves was significantly lower than at baseline. The high frequency component of heart rate variability was significantly lower after 12 minutes of Okinaga and lasted until 23 minutes. The low frequency/high frequency ratio was significantly lower after 18 minutes of Okinaga and until the end of the session. Okinaga produced relaxation, suggesting that deep breathing may relieve anxiety. However, study limitations include potential ambiguity in the interpretation of the low frequency/high frequency ratio, the small sample, and the fact that EEG was measured only on the forehead.

scholarly journals Autonomic Conditions in Tinnitus and Implications for Korean Medicine

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Eun Ji Choi ◽  
Younghee Yun ◽  
Seungyeon Yoo ◽  
Kyu Seok Kim ◽  
Jeong-Su Park ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Retrospective Chart Review ◽  
Frequency Component ◽  
Total Power ◽  
High Frequency Component ◽  
Chronic Patients ◽  
Research Attention ◽  
Korean Medicine ◽  
Significant Difference

Tinnitus patients suffer from not only auditory sensations but also physical, mental, and social difficulties. Even though tinnitus is believed to be associated with the autonomic nervous system, changes in autonomic conditions in tinnitus patients are not receiving much research attention. The aims of this study were to investigate the autonomic condition of tinnitus patients and to consider Korean medicine in the treatment of tinnitus with an evidence-based approach. We performed a retrospective chart review and compared the heart rate variability (HRV) parameters of 40 tinnitus patients (19 acute and 21 chronic) and 40 healthy controls. In tinnitus patients, the power of the high frequency component and total power of the HRV significantly decreased(P<0.05), and the low frequency to high frequency ratio significantly increased(P<0.05). There was no significant difference between the acute and chronic patients. When comparing each group with the controls, there was a tendency that the longer the duration of tinnitus was, the larger the observed HRV change was. In conclusion, tinnitus patients have vagal withdrawal and sympathetic overactivity, and chronic tinnitus more strongly affects autonomic conditions than acute tinnitus. This study provides evidence for Korean medical treatments of tinnitus, such as acupuncture and Qi-training, that cause modulation of cardiac autonomic function.

scholarly journals Different Coupling Modes Mediate Cortical Cross-Frequency Interactions

2015 ◽  
Author(s):  
Randolph F Helfrich ◽  
Christoph S Herrmann ◽  
Andreas K Engel ◽  
Till R Schneider
Keyword(s):  
Information Integration ◽  
Visual Processing ◽  
High Frequency ◽  
Low Frequency ◽  
Gamma Oscillations ◽  
Frequency Component ◽  
High Frequency Component ◽  
Alpha Power ◽  
Alpha Oscillation ◽  
Transcranial Alternating Current Stimulation

Cross-frequency coupling (CFC) has been suggested to constitute a highly flexible mechanism for cortical information gating and processing, giving rise to conscious perception and various higher cognitive functions in humans. In particular, it might provide an elegant tool for information integration across several spatiotemporal scales within nested or coupled neuronal networks. However, it is currently unknown whether low frequency (theta/alpha) or high frequency gamma oscillations orchestrate cross-frequency interactions, raising the question of who is master and who is slave. While correlative evidence suggested that at least two distinct CFC modes exist, namely phase-amplitude-coupling (PAC) and amplitude-envelope-correlations (AEC), it is currently unknown whether they subserve distinct cortical functions. Novel non-invasive brain stimulation tools, such as transcranial alternating current stimulation (tACS), now provide the unique opportunity to selectively entrain the low or high frequency component and study subsequent effects on CFC. Here, we demonstrate the differential modulation of CFC during selective entrainment of alpha or gamma oscillations. Our results reveal that entrainment of the low frequency component increased PAC, where gamma power became preferentially locked to the trough of the alpha oscillation, while gamma-band entrainment reduced alpha power through enhanced AECs. These results provide causal evidence for the functional role of coupled alpha and gamma oscillations for visual processing.

scholarly journals Forecasting Soil Moisture In The Soil Under The Caragana Shrubland Using Wavelet Analysis And NARX Neural Network

2021 ◽  
Author(s):  
Dong-Mei Bai ◽  
Zhong-Sheng Guo ◽  
Man-Cai Guo
Keyword(s):  
Neural Network ◽  
Soil Moisture ◽  
Wavelet Analysis ◽  
Soil Water ◽  
High Frequency ◽  
Sustainable Use ◽  
Low Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Narx Neural Network

Abstract Purpose: It is important for sustainable use of soil water resources to forecast soil moisture in forestland of water-limited regions. There are some soil moisture models. However, there is not a better method to forecast soil moisture.Methods: The change of soil moisture with time were investigated and the data of soil moisture were divided into a low frequency and a high frequency component using wavelet analysis, and then NARX neural network was used to build model I and model II. For model I, low frequency component was the input variable, and for model II, low frequency component and high frequency component were predicted.Results: the average relative error for model I is 3.5% and for model II is 0.3%. The average relative error of predicted soil moisture in100cm layer using model II is 0.8%, then soil water content in 40 cm and 200 cm soil depth is selected and the forecast errors are 4.9 % and 0.4 %.Using model II to predict soil water is well．Conclusion: Predicting soil water will be important for sustainable use of soil water resource and controlling soil degradation, vegetation decline and crop failure in water limited regions.

scholarly journals Antiforensics of Speech Resampling Using Dual-Path Strategy

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Diqun Yan ◽  
Yongkang Gong ◽  
Tianyun Liu
Keyword(s):  
High Frequency ◽  
Gaussian White Noise ◽  
Sampling Rate ◽  
Low Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Perceptual Quality ◽  
Median Filtering ◽  
Noise Perturbation

Resampling is an operation to convert a digital speech from a given sampling rate to a different one. It can be used to interface two systems with different sampling rates. Unfortunately, resampling may also be intentionally utilized as a postoperation to remove the manipulated artifacts left by pitch shifting, splicing, etc. To detect the resampling, some forensic detectors have been proposed. Little consideration, however, has been given to the security of these detectors themselves. To expose weaknesses of these resampling detectors and hide the resampling artifacts, a dual-path resampling antiforensic framework is proposed in this paper. In the proposed framework, 1D median filtering is utilized to destroy the linear correlation between the adjacent speech samples introduced by resampling on low-frequency component. And for high-frequency component, Gaussian white noise perturbation (GWNP) is adopted to destroy the periodic resampling traces. The experimental results show that the proposed method successfully deceives the existing resampling forensic algorithms while keeping good perceptual quality of the resampled speech.

scholarly journals Medical image fusion based on quaternion wavelet transform

2020 ◽  
Vol 14 ◽  
pp. 174830262093129
Author(s):  
Zhang Zhancheng ◽  
Luo Xiaoqing ◽  
Xiong Mengyu ◽  
Wang Zhiwen ◽  
Li Kai
Keyword(s):  
Wavelet Transform ◽  
Image Fusion ◽  
High Frequency ◽  
Medical Image ◽  
Low Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Medical Image Fusion ◽  
Quaternion Wavelet Transform ◽  
Fused Image

Medical image fusion can combine multi-modal images into an integrated higher-quality image, which can provide more comprehensive and accurate pathological information than individual image does. Traditional transform domain-based image fusion methods usually ignore the dependencies between coefficients and may lead to the inaccurate representation of source image. To improve the quality of fused image, a medical image fusion method based on the dependencies of quaternion wavelet transform coefficients is proposed. First, the source images are decomposed into low-frequency component and high-frequency component by quaternion wavelet transform. Then, a clarity evaluation index based on quaternion wavelet transform amplitude and phase is constructed and a contextual activity measure is designed. These measures are utilized to fuse the high-frequency coefficients and the choose-max fusion rule is applied to the low-frequency components. Finally, the fused image can be obtained by inverse quaternion wavelet transform. The experimental results on some brain multi-modal medical images demonstrate that the proposed method has achieved advanced fusion result.

The de Hass-van Alphen effect in aluminium

1957 ◽  
Vol 249 (965) ◽  
pp. 299-320 ◽  
Keyword(s):  
Fermi Surface ◽  
High Frequency ◽  
Oscillation Amplitude ◽  
Low Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Field Orientation ◽  
Principal Axes ◽  
Detailed Interpretation ◽  
Periodic Components

The de Haas-van Alphen effect in aluminium has been studied by measuring the oscillatory variation with magnetic field of the torque on a single crystal at liquid-helium temperatures in fields up to 15.4 kG. The torques were measured by an electronic feed-back device designed to reduce the twisting motion of the crystal during torque measurement. Particular attention was paid to the variation of the periods of the relatively high-frequency components of the oscillations with the orientation of the field relative to the crystal axes. A consistent interpretation was obtained by supposing that there are three such periodic components for each field direction, though often the relative amplitude of one or two of these is negligibly small. In terms of Onsager’s theory, the period is inversely proportional to the maximum area of cross-section of the Fermi surface by planes normal to the field, and the three periodic components have been shown to correspond to three identical cushion-shaped pieces of the Fermi surface with their principal axes mutually perpendicular. The location of these pieces in relation to the Brillouin zone is discussed and the characteristic dimensions of each piece have been calculated. Some results on the variation of the period of the relatively low-frequency component with field orientation in a (100) plane are described, but no detailed interpretation in terms of the shape of appropriate parts of the Fermi surface has been obtained. A few results on the variation of the oscillation amplitude with field orientation and on the temperature-dependence of amplitude are also presented. Alloying the aluminium with up to 0.26 % magnesium increases the period of the low-frequency component by about 2.3 % ; this suggests that this component arises from electrons rather than holes. The period of the high-frequency component is not significantly changed by alloying.

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